000 AXNT20 KNHC 112356 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 655 PM EST Wed Jan 11 2017 Tropical Weather Discussion for North America, Central America Gulf of Mexico, Caribbean Sea, northern sections of South America, and Atlantic Ocean to the African coast from the Equator to 32N. The following information is based on satellite imagery, weather observations, radar and meteorological analysis. Based on 1800 UTC surface analysis and satellite imagery through 2345 UTC. ...SPECIAL FEATURES... ...Atlantic Gale Warning... A 1009 mb low is centered 28N55W that is supported aloft by a mid to upper-level low nearly collocated with the surface feature near 29N56W. Its associated cold front extends from the low to 23N55W to 19N61W while a stationary front extends from the low to the north near 31N56W. Near gale to gale force northeast winds are prevailing within close proximity to the low within the northwest quadrant. These winds will continue through Thursday afternoon. Please see the latest NWS High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details. ...Caribbean Gale Warning... The pressure gradient generated between a surface high centered in the west Atlantic and lower pressures over the northern portion of South America will support gale-force winds from 10.5N-12N between 72W-75.5W starting tonight at 12/0600 UTC. These winds will pulse every night through the next 48 hours. Please see the latest NWS High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details. ...ITCZ/MONSOON TROUGH... The Monsoon Trough extends from the African coast near 09N13W to 05N20W. The Intertropical Convergence Zone extends from 05N20W to 03N34W to 01S46W. Isolated moderate convection is observed along the ITCZ between 32W-38W. ...DISCUSSION... GULF OF MEXICO... Mid-level ridging and dry air aloft noted on water vapor imagery supports a surface ridging that extends from across NE Florida southwestward to southern Mexico near 21N97W. Moderate to fresh anticyclonic winds are prevailing across the basin. Radar imagery depicts scattered showers moving across the Florida Straits and southeast Gulf waters. This overall synoptic pattern is expected to persist through the remainder of the week and into the weekend. The next front is expected to approach the region by late Tuesday. CARIBBEAN SEA... A broad surface high centered over the west Atlantic extends across the west Caribbean mainly north of 12N and west of 70W. A shear line extends across the central and east Caribbean from 11N84W to 17N63W. Isolated showers are observed along the shearline between 80W-84W. Scatterometer data depicts fresh to strong northeasterly winds behind the shear line including the Windward and Mona passage regions while moderate to fresh northeasterly winds prevail east of the line. The shear line is expected to remain nearly stationary or drift slightly southeastward through Thursday as it becomes diffuse by Thursday night into Friday. Scattered moderate convection is expected to develop over portions of northern Venezuela and Colombia as the shear line approaches. Gale force winds will develop across the waters north of Colombia starting tonight. Please refer to the section above for details. ...HISPANIOLA... Fresh to strong northeasterly winds prevail across the island and adjacent coastal waters. These winds are generated by a relatively strong pressure gradient across the region and southwest Atlantic waters. Isolated showers will continue as the northeast flow persists through the remainder of the week and the weekend. ATLANTIC OCEAN... A surface ridge prevails across the west Atlantic anchored by a 1033 mb high centered near 35N70W. To the east, a mid to upper- level low is centered near 29N56W supports a nearly collocated 1009 mb surface low, as mentioned in the Special Features section above. The associated cold front extends from the low to 18N62W. These features are supporting gale force winds in the central Atlantic. Please refer to the section above for details. Scattered showers and thunderstorms are observed east of the front/low mainly north of 22N between 48W-56W. The remainder of the basin dominated by a surface ridge anchored by a 1033 mb high near 43N25W. The low pressure area along the front are expected to drift southward through the remainder of the week and weaken well E of the Lesser Antilles by the weekend. Little change is expected elsewhere. For additional information please visit http://www.hurricanes.gov/marine $$ ERA